Ground anchor for use with natural ground cover

ABSTRACT

A biodegradable ground anchor for use in conjunction with a ground cover. The anchor includes a head portion that has opposite surfaces and a peripheral surface. A pair of integral legs depend away from one of the opposite surfaces. The legs are generally parallel with respect to each other. Each of the legs includes a pair of fins. The distal end of each leg terminates in a point. The ground anchor is made from a polylactide polymer that is biodegradable.

BACKGROUND OF THE INVENTION

[0001] Soil erosion has been a concern for a number of years. In many types of construction projects the movement or excavation of soil has left soil bare and subject to erosion. One exemplary excavation project is road construction. While grass seed or other ground cover may be planted on the bare soil, the seed may be washed away before it can grow so that erosion may still be a problem.

[0002] In an effort to combat soil erosion, there has been developed a soil erosion control blanket. One such blanket is the Robexshield™ RS-1 straw erosion control blanket. U.S. Pat. No. 5,786,281 to Prunty et al. also shows an erosion control blanket. Typically, erosion control blankets have been placed on the bare soil and then attached to the ground via ground spike or spikes. Ground spikes are positioned in a pattern so as to securely attach the soil erosion control blanket to the ground. Over the course of time it is not unusual for the ground spikes to work themselves in a direction so that the upper end of the ground spike is exposed above the surface of the ground.

[0003] As the grass or other ground cover grows it will become necessary to mow the grass or the ground cover. When mowing in an area in which ground spikes have a portion exposed above the ground, there is a reasonable possibility that the mower blade may impact the ground spike so as to pull it out of the ground and project it away from the mower. In another type of occurrence, the mower blade may impact a ground spike fully inserted into the ground when the blade scraps or digs into the ground. Either one of these occurrences can result in the ground spike being projected towards a person such as occupants of a motor vehicle in the case of road side mowing thereby exposing such persons to the dangers connected with being struck with the flying ground spike. It this becomes apparent that there would be a benefit if there would be a ground anchor that did not have the tendency to work its way up out of the ground. This could occur through the use of structure that would help maintain the ground anchor in the ground.

[0004] Still referring to the potential harm associated with a mower blade striking a ground spike, it would also be desirable if there would be a ground anchor that had a structure so that it would not be able to be effectively projected upon impact with a mower blade. For example, that the ground anchor would have the tendency to disintegrate upon impact with the mower blade.

[0005] In the case of steel ground spikes, and even ground spikes made out of other material, the absence of a biodegradable property or the presence of a slow biodegradable property can be undesirable. It would thus be desirable to provide a ground anchor that is biodegradable. It would also be desirable to provide a ground anchor that remains biodegradable only for an amount of time sufficient (or that can be designed to remain biodegradable only for an amount of time sufficient) to secure the soil erosion control blanket for an adequate period of time until there is no longer a need for the erosion control blanket. For example it would be desirable to provide a ground anchor that decomposed at a predetermined rate so that at the time of the first mowing (or at least during the earlier mowings) it would not have the structural integrity to be projected (or projected any significant distance) upon impingement with a mower blade.

[0006] Heretofore, ground spikes have been generally driven into the ground by hand to secure the erosion control blanket. The nature of this activity is inherently physically detrimental to the worker. It would thus be desirable to provide a ground anchor that could be driven by a gun or the like so as to decrease the physical stress to the worker.

SUMMARY OF THE INVENTION

[0007] In one form thereof, the invention is a biodegradable ground anchor for use in conjunction with a ground cover. The anchor includes a head portion that has opposite surfaces and a peripheral surface. A pair of integral legs depend away from one of the opposite surfaces. The legs are generally parallel with respect to each other. Each of the legs includes a pair of fins. The distal end of each leg terminates in a point. The ground anchor is made from a polylactide polymer that is biodegradable.

[0008] In another form thereof, the invention is a ground cover blanket system that comprises a ground cover blanket that has cross-hatched members and a biodegradable ground anchor. The ground anchor has a head portion with opposite surface surfaces and a peripheral surface. The anchor also has a pair of legs that depend away from one of the opposite surfaces wherein the legs are generally parallel with respect to each other. Each of the legs includes a pair of fins. The distal leg of each leg terminates in a point. The ground anchor being made from a polylactide polymer that is biodegradable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Set forth below is a brief description of the drawing figures that make up a part of this patent application:

[0010]FIG. 1 is an isometric view of an erosion control blanket positioned on the ground (or earth strata) and earth strata sectioned away so as to show a ground anchor (10) prior to entry into the earth strata, a ground anchor (10A) partially into the ground, and a ground anchor (10B) fully inserted into the ground;

[0011]FIG. 2 is an isometric view of a first specific embodiment of a ground anchor wherein a portion of the head section of the ground anchor is broken away to show the joinder of the leg to the head portion;

[0012]FIG. 3 is an isometric view of a second specific another embodiment of a ground anchor wherein the ground anchor has a round head;

[0013]FIG. 3A is an isometric view of a gun (along the line of a double barreled shotgun) that installs (or drives) the ground anchors shown in FIG. 3 into the ground;

[0014]FIG. 4 is an isometric view of a third specific embodiment of a ground anchor wherein the ground anchor has a square head; and

[0015]FIG. 5 is a side view of the ground anchor shown in FIG. 2.

DETAILED DESCRIPTION

[0016] Referring to the drawings, FIG. 1 illustrates a specific embodiment of the ground anchor generally referred to as 10 in conjunction with a soil erosion control blanket 12. Although other blankets may be applicable to use, one preferred blanket is the RS-1 Straw Erosion Control Blanket made by Robexshield, 5830 Highway 161, Springfield, Tenn. 37172. Applicants also contemplate that the ground anchors of the present invention may be used in conjunction with various types of ground cover (e.g., turf, seed blankets, and the like) wherein the ground cover must be secured to the ground.

[0017] Soil erosion control blanket 12 is shown rolled out on top of the ground. The blanket 12 is essentially flat on the surface of the ground 14. Referring to the position of the ground anchors, ground anchor 10 is shown in a position above the ground prior to being driven into the ground. The ground anchor designated as 10A is a ground anchor that has been partially driven into the ground. The ground anchor designated as 10B is a ground anchor that has been completely driven into the ground so as to engage a part of the blanket 12 and thereby attach the blanket 12 to the ground (or earth strata) 14. As can be appreciated, a number of different nailing or stapling arrangements of the ground anchors 10 may be used to attach the blanket 12 to the ground 14.

[0018] Referring to FIG. 2, the ground anchor 10 includes an oval head 16 at the upper end thereof. In the drawing a portion of the head 16 is broken away. Head 16 has a top surface 18 and an oval peripheral surface 20. Head 16 further includes a bottom surface 24.

[0019] A pair of generally parallel legs 26 depends from the head 16 of the ground anchor 10. Although it is not illustrated in the drawings, for manufacturing purposes a small tab extends between the legs to maintain the position of the legs while they are still hot or warm from the injection molding operation. The legs 26 are integral with the head 16.

[0020] Each one of the legs 26 has an upper (proximal) end 28 that joins the bottom surface 24 of the head 16. Each leg 26 also has a distal end 30 that comprises a sharp point. The distal end 30 (or point) is the termination of the tapered (or conical) portion 32 adjacent the distal end 30. Each leg 26 has two pairs of fins 36 and 38 spaced between the proximal end 28 and the distal end 30. These fins 36, 38 are positioned closer to the distal end 30 than to the proximal end 28. Each fin 36, 38 has a chevron shape. Each fin 36, 38 is swept back in the direction of the proximal end 28 so that these fins 36, 38 resist the tendency of the ground anchor 10 to work its way out of the ground.

[0021] Referring to FIGS. 2 and 6, the overall length of the ground anchor is dimension “A”. The longitudinal dimension of the head 16 is dimension “B”. The transverse dimension of head 16 is dimension “C”. The thickness of head 16 and legs 26 is dimension “D”. The spacing of the legs 26 is dimension “E”. Exemplary dimensions and ranges of dimensions are set forth in Table 1 below that presents the above dimensions. TABLE 1 Dimensions Of Ground Anchor Dimension Magnitude (Inches) A 2.0-6.0 B 1.375 C 0.5  D .150-.190 E 1.0 

[0022] It should be appreciated that there is no intention to restrict the present invention to the above dimensions. These dimensions may vary depending upon the specific application for the ground anchor.

[0023] Referring to FIG. 3, the ground anchor as generally designated 50 includes a round head 52 at the upper end thereof. Head 52 has a top surface 54 and a round peripheral surface 56 Head 52 further includes a bottom surface (not shown). A pair of generally parallel legs 58 depend from the head 52 of the ground anchor 50. Legs 58 are integral with the head 52. As mentioned earlier, there is a small tab 63 of material that extends between the legs to maintain their position while still hot or warm after the injection molding operation. Each one of the legs 58 has an upper (proximal) end that joins the bottom surface of the head 52. Each leg 58 also has a distal end 66 that comprises a sharp point. The distal end 66 (or point) is the termination of a tapered (or conical) portion 64. Each leg 58 has two pairs of fins 60 and 62 spaced between the proximal end and the distal end 66. These fins 60, 62 are positioned closer to the distal end 66. Each fin 60, 62 has a chevron shape so that each fin 60, 62 is swept back in the direction of the proximal (or upper) end. These fins (60,62) resist the tendency of the ground anchor 50 to work its way out of the ground.

[0024] Referring to FIG. 3A, the ground anchor 50 is shown in conjunction with a anchor gun 100. The purpose of the anchor gun 100 is to drive the ground anchors 50 into the ground without the workers having to bend over each time as is required with manually driving or nailing the anchors into the ground. It is physically easier and leads to less of a chance for physical injury if the worker does not have to bend over each time, but instead, can use a anchor gun along the lines of anchor gun 100 which does not require the worker to bend over for installation of each anchor.

[0025] Anchor gun 100 has a firing mechanism enclosed by a housing 102 and a handle 104 that extends from the housing 102. As one option, the firing mechanism may be pneumatically driven. The anchor gun 100 further has a trigger 106. The anchor gun 100 is shown as having two barrels 108 wherein the anchors 50 feed into the barrels 108 through openings 110. The length of each one of the barrels 108 is such so that the worker does not have to bend over to insert a anchor into the ground. By using the anchor gun 100, the worker does not have to bend over and manually drive the ground anchor into the ground. It should be appreciated that the anchor gun may take on any one of a number of different configurations so as to be useful for the insertion of ground anchors into the ground.

[0026] Referring to FIG. 4, the ground anchor generally designated as 70 includes a square head 72 at the upper end thereof. Head 72 has a top surface 74 and a square peripheral surface 76. Head 72 further includes a bottom surface. A pair of generally parallel legs 78 depend from the head 72 of the ground anchor 70. Legs 78 are integral with the head 72. Like for the above embodiments, for a manufacturing viewpoint it is preferred that a small tab of material extends between the legs so as to maintain their position after injection molding while the part is still hot or warm and subject to deformation.

[0027] Each one of the legs 78 has an upper (proximal) end that joins the bottom surface of the head 72. Each leg 78 also has a distal end 86 that comprises a sharp point. The distal end 86 (or point) is the termination of a tapered (or conical) portion 84. Each leg 78 has two pairs of fins 80 and 82 spaced between the proximal end and the distal end 86. Each fin 80, 82 has a chevron shape so that each fin 80, 82 is swept back in the direction of the proximal end. Like for the other fins, these fins (80, 82) resist the tendency of the ground anchor 70 to work its way out of the ground.

[0028] Ground anchors 10, 50 and 70 are made from an injection moldable polymer that is biodegradable. One example of such a material is PLA Polymer 3000D sold by Cargill Dow Natureworks®, 15305 Minnetonka Blvd., Minnetonka, Minn. 55345. According to published literature, the PLA Polymer 3000D is a polyactide resin. Based upon information from published literature, the Tables 2 and 3 below present the typical processing temperature profile of PLA Polymer 3000D and the Typical Material Application Properties for PLA Polymer 3000D. TABLE 2 Processing Temperature Profile Melt Temperature 390° F. (200° C.) Feed Throat  70° F. (20° C.) Feed Temperature (crystalline pellets) 330° F. (165° C.) Feed Temperature (amorphous pellets) 300° F. (150° C.) Compression Section 380° F. (195° C.) Metering Section 400° F. (205° C.) Nozzle 400° F. (205° C.) Mold  75° F. (25° C.) Screw Speed 100-175 rpm Back Pressure  50-100 psi Mold Shrinkage .004 in/in. +/− .001

[0029] In the processing of the material, applicant prefers that the injection molding occur at a temperature that range between about 380 degrees Fahrenheit and about 431 degrees Fahrenheit. TABLE 3 Typical Material Application Properties PLA Resin ASTM (General Purpose Method Physical Properties Specific Gravity 1.21 D792 Melt Index, g/10 min (190 C/2.16 K° 10-30 D1238 Clarity Transparent Mechanical Properties Tensile Yield Strength, psi (MPa)  7,000 (48) D638 Tensile Elongation, % 2.5 D638 Notched Izod Impact, ft-lb/in (j/m)   0.3 (0.16) D256 Flexural Strength (MPa)  12,000 (83) D790 Flexural Modulus (MPa) 555,000 (3828) D790

[0030] According to literature, the PLA polymer 3000D has been shown to biodegrade in a fashion similar to paper under simulated composting conditions per ASTM D5338 at 50 degrees Centigrade. Although the soil conditions may vary, it is applicant's intention that the ground anchor will biodegrade at a rate such that as of the time of the first mowing (or the second mowing) in the case of ground cover that the ground anchor will not have the structural integrity to be propelled upon impingement by a lower blade. It is also applicant's intention that the ground anchor will have sufficient structural integrity so as to maintain the soil erosion control blanket in position for the extent necessary. Applicant notes that the time it takes for the anchor to biodegrade can be varied by varying the thickness of the anchor. For example, a thinner anchor would be expected to degrade sooner than a thicker anchor.

[0031] All patents, patent applications, articles and other documents identified herein are hereby incorporated by reference herein.

[0032] Other embodiments of the invention may be apparent to those skilled in the art from the consideration of the specification or the practice of the invention disclosed herein. It is intended that the specification and any examples set forth herein be considered as illustrative only, with the true spirit and scope of the invention being indicated by the following claims. 

1. A biodegradable ground anchor for use in conjunction with a ground cover, the anchor comprising; a head portion having opposite [surface] top and bottom surfaces and a peripheral surface; a pair of integral legs depending away from one of the opposite surfaces, the legs being generally parallel with respect to each other; each of the legs including a pair of fins; the distal end of each leg terminating in a point intended to assist in penetrating the ground; and the ground anchor being made From a polyactide polymer that[s] is biodegradable.
 2. A ground cover blanket system comprising: a ground cover blanket, the blanket having cross-hatched members; a biodegradable ground anchor for penetrating the ground, the ground anchor comprising a head portion having opposite [surface] top and bottom surfaces and a peripheral surface; a pair of legs depending away from one of the opposite surfaces, the legs being generally parallel with respect to each other; each of the legs including a pair of fins; the distal leg of each leg terminating in a point; and the ground anchor being made from a polylactide polymer that is biodegradable.
 3. The ground cover blanker system of claim 2 wherein the groundcover blanket is a soil erosion control blanket.
 4. The ground anchor of claim 1 wherein the head portion being generally rectangular in shape.
 5. The ground anchor of claim 1 wherein the head portion being generally square in shape.
 6. The ground anchor of claim 1 wherein the head portion being generally oval in shape.
 7. The ground anchor of claim 1 wherein the head portion being generally circular in shape.
 8. The ground anchor of claim 1 wherein the legs depend away from the bottom surface of the head portion.
 9. A biodegradable ground anchor for use in conjunction with a ground cover wherein the ground anchor is driven into the ground so as to retain the ground cover to the ground, the ground anchor comprising: a head portion having opposite top and bottom surfaces and a peripheral surface, and the top surface of the head portion being impacted upon the ground anchor being driven into the ground; a pair of integral legs depending away from the bottom surface of the head portion, the legs being generally parallel with respect to each other, and the legs being sufficient rigid so as to maintain their structural integrity upon being driven into the ground; each of the legs including a pair of chevron-shaped fins; the distal end of each leg terminating in a point that assists in the ground anchor penetrating the ground; and the ground anchor being made from a polylactide polymer that is biodegradable so that the structural integrity of the ground anchor diminishes as the ground anchor remains in the ground. 